• Bulletin of the Korean Chemical Society
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• 제13권6호
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• pp.680-683
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• 1992

The electrochemistry of benzidine and hydrazobenzene was studied in water-acetonitrile mixed solutions at various pHs and the results are reported. The cyclic voltammetric peak for the oxidation of benzidine shows a pH dependency of -62 mV/pH in the pH range of 0-3.5, no pH dependency between pH values of 3.5 and about 10.5, and of about -50 mV/pH between pH=10.50 and 14.0, indicating that oxidation mechanisms differ depending on the pH of the medium. However, the CV peak for the hydrazobenzene oxidation is shown to be independent of pH of the medium, suggesting that the proton is not involved in the rate limiting step of the electrochemical oxidation of hydrazobenzene to azobenzene. Results of in situ spectroelectrochemical experiments indicate that the oxidation products obtained during the oxidation of benzidine and hydrazobenzene depend on the result of dynamic equilibria taking place at various pHs.

• Bulletin of the Korean Chemical Society
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• 제6권2호
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• pp.115-118
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• 1985

The oxidation of hydrazobenzene by oxygen in methanol solution is catalysed by Co(3MeOsalen) which is a synthetic oxygen carrier. The products are trans-azobenzene and water. The rate of the reaction has been studied spectrophotometrically and the rate law established. A mechanism involving a ternary complex of catalyst, hydrazobenzene and oxygen has been proposed.

• Bulletin of the Korean Chemical Society
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• 제27권2호
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• pp.255-265
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• 2006

The oxidation of hydrazobenzene by molecular oxygen in the polar solvent methanol is catalysed by a Schiff's base complex Co(3MeOsalen) which is a synthetic oxygen carrier. The products are trans-azobenzene and water. The rate of the reaction has been studied spectrophotometrically and the rate law established. A mechanism involving a ternary complex of catalyst, hydrazobenzene and molecular oxygen has been proposed. The kinetic studies show that a ternary complex $CoL{\cdot}H_2AB{\cdot}O_2$ is involved in the rate determining step. The reactions are summarised in a catalytic cycle. The kinetic data suggest that a ternary complex involving Co(3MeOsalen), triphenyl-phosphine and molecular oxygen is catalytically acive species but at higher triphenylphosphine concentrations the catalyst becomes inactive. The destruction of the catalytic activity could be due to the catalyst becoming coordinated with triphenyl phosphine at both z axis sites of the complex e.g. Co (3MeOsalen)$(PPh_3)_2$.

• 대한화학회지
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• 제38권4호
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• pp.302-308
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• 1994

산소가 포화된 메탄올 용액에서 다섯자리 Schiff base cobalt(II) 착물인 [Co(II)(Sal-DPT)(H$_2$O)] 와 [Co(II)(Sal-DET)(H$_2$O)]들의 활성촉매에 의한 hydrazobenzene(H$_2$AB)의 산화 주생성물은 trans-azobenzene(trans-AB)이다. UV-visible분광광도법에 의해 이들 반응의 속도상수 $k=6.06{\times}10^{-3}sec^{-3}$ 및 $2.50{\times}10^{-3}sec^{-1}$로 주어짐을 알았다. 균일 산화 활성촉매에 의한 H$_2$AB의 산화반응 메카니즘은 다음과 같은 과정으로 주어진다. H$_2$AB + Co(II)(L)(H$_2$O) + O$_2$ $\rightleftharpoons^K_{methanol}Co(III)(L)O_2{\cdot}H_2AB + H_2O\longrightarrow^{k}Co(II)(L) + trans-AB + H_2O_2$ (L: Sal-DPT and Sal-DET).

• 대한화학회지
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• 제47권6호
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• pp.585-590
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• 2003

코발트 산소 운반체인 N,N''-ethylenebis(3-methoxysalycylideneiminato)cobalt(II), Co(3MeOsalen)을 $25{\circ}C$에서 합성하였다. 이 착물과 하이드라조벤젠의 자외선 및 가시부분 광스펙트럼은 파장 범위 200-600 nm에서 비수용매 메탄올을 사용하여 연구하였다. 하이드라조벤젠의 산소와의 산화반응은 메탄올에서 Co(3MeOsalen) 촉매로 사용하였다. 트라이페닐포스핀($PPh_3$) 존재하에서, 반응속도는 감소하였으며 이는 촉매가 리간드 트라이페닐포스핀과 배위화합된 것으로 추정되며 촉매가 비활성인 Co(3MeOsalen)$(PPh_3)_2$으로 되어 속도가 급격히 떨어지는 것으로 생각된다. 리간드 트라이페닐포스핀과 하이드라조벤젠의 초기산화속도는 이론속도식, Rate=$k_1+k_2K_1[P]/1+K_1[P]+K_1K_2[P]^2$으로 측정되었다. 이것은 리간드가 메탄올 분자보다 더 좋지않은 σ-주게일 것으로 간주된다.

• 대한화학회지
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• 제36권6호
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• pp.894-905
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• 1992

산소가 포화된 메탈올 용액에서 Superoxo형인 [Co(Ⅲ)(SED)(Py)$O_2$]와 [Co(III)(SOPD)(Py)$O_2$]들의 균일 산화 활성 촉매에 의한 hydrazobenzene(H2AB)의 산화 주생성물은 trans-azobenzene (t-AB)이고 반응 속도상수 k = 7.692 ${\times}$ $10^{-2}$ M/sec 및 5.076 ${\times}$ $10^{-2}$ M/sec이나 ${\mu}$-peroxo형인 [Co(III)(SED)(Py)]$_2O_2$에 의한 주생성물은 cis-azobenzene (c-AB)이 선택적으로 생성되고 반은 속도상수 k = 1.266 ${\times}$ $10^{-2}$ M/sec로 주어짐을 UV-visible 흡광도법으로 알아보았다. 이들 산화반응은 다음과 같이 균일 산소 첨가 착물촉매에 의하여 산화주생성물이 선택적으로 다르게 생성된다. $H_2$AB + Co(II)(Schiff base)$(Py)_2$ + $O_2$ ${\rightleftharpoons}_{MeOH}^K$ Co(III)(Schiff base)(Py)$O_2$${\cdot}$$H_2$AB + Py $\longrightarrow^k$ Co(II)(Schiff base)$(Py)_2$ + t-AB + $H_2O_2$(Scchiff base : SED 및 SOPD). $H_2$AB + 2Co(II)(SND)$(Py)_2$ + $O_2$ ${\rightleftharpoons}_{MeOH}^K$ [Co(III)(SND)(Py)]$_2O_2$${\cdot}$$H_2$AB + 2Py $\longrightarrow^k$ (Co(II)(SND)$(Py)_2$ + c-AB + $H_2O_2$.

• 대한화학회지
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• 제36권2호
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• pp.261-272
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• 1992

네자리 Schiff base의 착물 Co(II)(3MeOSED)$(H_2O)_2$을 합성하였다. 이 착물의 균일 산화 활성촉매로서 산소첨가 착물은 DMF와 DMSO 용매에서는 ${\mu}$-peroxo형인 [Co(III)(3MeOSED)(DMF)]$_2O_2$와 [Co(III)(3MeOSED)(DMSO)]$_2O_2$이나 pyridine 용매에서는 superoxo형인 [Co(Ⅲ)(3MeOSED)(Py)]$O_2$로 주어진다. 이들의 CV법과 DPP법에 의한 전기화학적인 특성으로 ${\mu}$-peroxo형은 3단계 환원과정으로 일어나지만, superoxo형은 $O_2$의 prewave를 포함한 4단계 환원과정으로 일어난다. 산소가 포화된 메탄올 용액에서 [Co(III)(3MeOSED)(L)]$O_2(L: CH_3OH)$ 의 균일 산화 활성촉매에 의한 hydrazobenzene-$(H_2AB)$의 산화 주생성물은 trans-azobenzene(t-AB)이 선택적으로 다음과 같은 반응식으로 생성되고 이 때 속도상수는 k = (2.96 ${\pm}$ 0.2) ${\times}$ $10^{-1}$M/sec임을 알았다. $H_2AB$ + Co (Ⅱ)(3MeOSED)$(L_2)+O_2\;{\rightleftarrow^K}$ [Co(III)(3MeOSED)(L)]$O_2{\cdot}H_2AB{\longrightarrow^K}$ Co(II(3MeOSED)$(L)_2$+t-AB+$H_2O_2 $.

• 대한화학회지
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• 제21권6호
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• pp.404-412
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• 1977

에탄올-물 혼합용매에서 납전극을 사용하여 니트로벤젠(${\phi}NO_2$)과 그 유도체의 전해 환원반응을 조사하였다. 산성용액에서는 퍼텐셜에 따라 ${\phi}NHOH\;및\;{\phi}NH_2$가 생성되었으며 니트로벤젠(${\phi}NO$)은 중간체가 아닌것으로 보였다. 염기성 용액에서는 ${\phi}NO$가 생성되며 더 낮은 퍼텐셜에서 환원시키면 ${\phi}N=N{\phi}$ 등 짝지어진 화합물이 생성됨을 확인하였다. 사용한 전해질 용액에서 ${\phi}NO\;와\;{\phi}NHOH$ 사이에 화학적인 짝지음 반응(coupling reaction)은 일어나지 않았다. 각각의 반응에 대해 전류-전압관계와 pH 의존도 및 반응물질에대한 반응 차수로부터 반응 메카니즘을 도출하였다. ${\phi}NO$가 생성되는 반응은 치환기가 있을 때도 같은 메카니즘을 따르는 것으로 보인다.

• Bulletin of the Korean Chemical Society
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• 제13권2호
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• pp.199-207
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• 1992

The approximate rates and stoichiometry of the reaction of excess sodium diethyldihydroaluminate (SDDA) with 68 selected organic compounds containing representative functional groups were examined under standard conditions (THF-toluene, $0^{\circ}C$ in order to compare its reducing characteristics with lithium aluminum hydride (LAH), aluminum hydride, and diisobutylaluminum hydride (DIBAH) previously examined, and enlarge the scope of its applicability as a reducing agent. Alcohols, phenol, thiols and amines evolve hydrogen rapidly and quantitatively. Aldehydes and ketones of diverse structure are reduced rapidly to the corresponding alcohols. Reduction of norcamphor gives 11% exo-and 89% endo-norborneol. Conjugated aldehydes such as cinnamaldehyde are rapidly and cleanly reduced to the corresponding allylic alcohols. p-Benzoquinone is mainly reduced to hydroquinone. Hexanoic acid and benzoic acid liberate hydrogen rapidly and quantitatively, however reduction proceeds very slowly. Acid chlorides and esters tested are all reduced rapidly to the corresponding alcohols. However cyclic acid anhydrides such as succinic anhydride are reduced to the lactone stage rapidly, but very slowly thereafter. Although alkyl chlorides are reduced very slowly alkyl bromides, alkyl iodides and epoxides are reduced rapidly with an uptake of 1 equiv of hydride. Styrene oxide is reduced to give 1-phenylethanol quantitatively. Primary amides are reduced very slowly; however, tertiary amides take up 1 equiv of hydride rapidly. Tertiary amides could be reduced to the corresponding aldehydes in very good yield ( > 90%) by reacting with equimolar SDDA at room temperature. Hexanenitrile is reduced moderately accompanying 0.6 equiv of hydrogen evolution, however the reduction of benzonitrile proceeds rapidly to the imine stage and very slowly thereafter. Benzonitrile was reduced to give 90% yield of benzaldehyde by reaction with 1.1 equiv of hydride. Nitro compounds, azobenzene and azoxybenzene are reduced moderately at $0^{\circ}C$, but nitrobenzene is rapidly reduced to hydrazobenzene stage at room temperature. Cyclohexanone oxime is reduced to the hydroxylamine stage in 12 h and no further reaction is apparent. Pyridine is reduced sluggishly at $0^{\circ}C$, but moderately at room temperature to 1,2-dihydropyridine stage in 6 h; however further reaction is very slow. Disulfides and sulfoxides are reduced rapidly, whereas sulfide, sulfone, sulfonic acid and sulfonate are inert under these reaction conditions.